The present invention relates to cured-in-place pipe lining. More specifically, but not exclusively, the present invention relates to apparatus and methods for lining from a larger diameter pipe to a smaller diameter pipe.
As the infrastructure of major cities and towns in the developed world age, the sewer systems weaken. Pipe degradation, system blockage, water infiltration, and sewer leakage are major problems that aging sewer systems experience. As these problems persist, the sewer system may eventually experience total failure and entire sections of the sewer system may collapse. As a result, sinkholes may form and sewers may back up into homes and places of business. One method of addressing this critical infrastructure problem is the use of pipe lining techniques to rehabilitate existing sewer systems.
Cured-in-place pipelining (CIPP) is one such technique that includes rehabilitating an existing sewer system by creating a new pipe within an existing pipe. A liner, impregnated with a resinous material capable of curing and hardening, is inverted or pulled into a damaged pipe. The liner is pressed against the wall of the existing pipe, and the resinous material is allowed to cure and harden. The result is a replacement pipe having the older pipe or “host pipe” on the exterior. The cured-in-place pipe acts to alleviate the problems caused by structural defects and blockages in the existing sewer system.
It is not uncommon that a pipe will have a change in diameter. For example, a lateral sewer pipe could have an inside diameter of 6 inches for the first foot of pipe extending from a main sewer pipe and then transition to a 4-inch diameter pipe. One way of dealing with this change in pipe diameter is to custom manufacture the lateral liner. This would normally require taking measurements in the field, sending the information to a liner manufacturer, fabricating the custom liner, and then installing the liner at a later date. This time-consuming process and additional labor to pre-measure the pipe adds to the cost of the project.
The pipe measurements must also be precise. In the example of the 6-inch pipe section adjacent to a 4-inch pipe section described above, the contractor would not want to line the 4-inch pipe with a larger diameter liner. As such, there is an incentive to have the custom liner made such that the larger diameter portion is shortened to ensure that the smaller diameter liner is actually entering the smaller diameter pipe. Yet it is desirable that the liner be compressed against the host pipe. If not constrained, one could overstretch the liner, causing resin to ring out of the liner with gravity pulling the resin to the bottom of the host pipe.
There is therefore a need in the art for an improved apparatus and methods for lining a pipe line with different diameters.